According to the related art, a multi-projection system which projects an image using a plurality of projectors is known. The multi-projection system may have a mode in which images from individual projectors are projected to different places, a mode in which images are arrayed in tiling manner to form a single image and this single image is projected, a mode in which images are projected in a superimposed state (stack projection), and the like. In such a multi-projection system, depending on the installation positions and projection angles of the plurality of projectors, the correspondence between the projectors and the projection images may be hard to grasp in some cases. If which projector projects which image is not known as in such cases, the projection image from an unintended projector may be adjusted erroneously at the time of adjusting the projection image from each projector. Thus, PTL 1 discloses a projector which projects and displays an ID that is set for the projector (display control device), on a projection surface.